#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;

int n;
ll m;
struct Node {
  int x, y;
  ll t;
  bool operator<(Node b) const {
    if (x != b.x)
      return x < b.x;
    else
      return t > b.t;
  }
} a[N];
ll b[N];
int bit[N];
void init() { rep(i, 1, n) bit[i] = 0; }
int lowbit(int x) { return x & -x; }
void update(int x, int d) {
  for (int i = x; i <= n; i += lowbit(i)) bit[i] += d;
}
int query(int x) {
  int sum = 0;
  for (int i = x; i > 0; i -= lowbit(i)) sum += bit[i];
  return sum;
}

bool check(ll k) {
  rep(i, 1, n) a[i].t = a[i].y - a[i].x * k;
  rep(i, 1, n) b[i] = a[i].t;
  sort(b + 1, b + n + 1);
  int num = unique(b + 1, b + n + 1) - b - 1;
  rep(i, 1, n) a[i].t = lower_bound(b + 1, b + num + 1, a[i].t) - b;
  sort(a + 1, a + n + 1);
  init();
  ll ans = 0;
  rep(i, 1, n) {
    ans += query(a[i].t);
    update(a[i].t, 1);
  }
  return ans >= m;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> m;
  rep(i, 1, n) cin >> a[i].x >> a[i].y;
  int l = -2e8, h = 2e8;
  while (l <= h) {
    int mid = (l + h) >> 1;
    if (check(mid))
      l = mid + 1;
    else
      h = mid - 1;
  }
  cout << l - 1;
  return 0;
}